6) A civil service exam yields scores which are normally distributed with a mean of 81 and a standard deviation of 5.5. If the civil service wishes to set a cut-off score on the exam so that 15% of the test takers fail the exam, what should the cut-off score be? Remember to round your zvalue to 2 decimal places. 0 75.28 0 86.72 0 60.24 0 64.56 0 None ofthe above 7) Based on FAA estimates the average age of the eets of the 10 largest U.S. commercial passenger carriers is 13.4 years with a standard deviation of 1.7 years. Suppose that 40 airplanes were randomly selected from the eets of these 10 carriers and were inspected for cracks in these airplanes that are considered too large for ying. What is the probability that the average age of these 40 airplanes is at least 14 years old? Round your answer to 4 decimal places. Remember to round your z-value to two decimal places. 0 0.01 29 0 0.2654 0 0.3589 0 0.4731 0 None of the above 8) Out of a total of 10 college textbooks estimate the standard deviation of their ages if the oldest textbook is known to be 7.9 years old and the newest textbook is 1.3 years old. 0 0.5 years 0 1.1 years 0 2.3 years 0 2.9 years 0 3.3 years 9) In the California Community Colleges an undergraduate student survey was taken that compares the class of the student to their opinion on whether or not they favor or oppose same sex marriages. The following data is a summary of the survey taken by questioning 500 undergraduate students. If a student from the survey is selected at random, then nd the probability that the student favors same sex marriages, given that the student is not a Senior Fresh Soph Junior Senior Totals Favor 85 74 64 53 276 Oppose 61 60 55 48 224 Totals 146 134 119 101 500 0 223/500 0 276/399 0 223/399 0 399/500 10) Assume that the average full time college student in the U5. requires a total of $10,500 per year to cover the costs of tuition, books and fees with a standard deviation of $1,300. If 50 full time students are randomly sampled in the US, what is the probability that their total annual costs for tuition, books and fees exceed $550,000? Round your answer to 4 decimal places. Remember to round your zvalue to 2 decimal places